Expression of genes encoding neuropeptides and enzymes in the brain with emphasis on the hypothalamus are being studied. We have concentrated on preparing a "knock-out" the oxytocin gene in mice through homologous recombination. Chimeric mice have been generated and heterozygoses are being sought. We also demonstrated that the oxytocin receptor is unregulated in the kidney after estrogen administration suggesting and explanation for the fluid shifts experienced during pregnancy and the menstrual cycle. we are also studying the novel POU protein RHS2 (Brain-4) whose full- length cDNA we previously cloned. We have mapped the sites of expression including during development in t he mouse of the four class III POU proteins to further our understanding of their roles. We have also determined that the class III proteins interact with each other in far- western and two-hybrid assays. We are also trying to determine with what other proteins Brain-4 interacts. Mapping of gene expression the human hypothalamus continues: analyses of vasopressin, oxytocin, LHRH, and the opiods have been published. Maps of the tachykinins, corticotropin-releasing factor somatostatin, and growth hormone-releasing factor are in progress. We are attempting to improve the technique of differential displays to isolate the gene encoding the serotonin N-acetyltransferase from pineal gland. We have isolate several pineal-specific genes that we are currently evaluating.